The relationships between the smooth muscle of the gastrointestinal tract and peptic ulcers have not been clarified. Muscle activity is important in controlling stomach emptying, mixing and propulsion. An alteration in the function of the smooth muscle could conceivably be an important factor in various disease states, especially in ulcerogenic sequelae. Using dogs as the model, we shall develop an experimental surgical approach that will produce ulcers in the small intestine. In addition, drugs will be used as pharmacological probes to highlight the muscle properties as ulcers are produced or prevented. The altered gastrointestinal tract will be monitored for its mechanical and electrical activity. This is performed with implanted electrodes and transducers in unanesthetized chronic dog preparations. These studies should reveal the role of the smooth muscle in initiating a peptic ulcer in the small bowel.